This invention relates to dipeptide sweeteners having improved solubility without significant loss of original sweetness. More specifically, it relates to the preparation of the inorganic salts of the dipeptide sweeteners.
It has recently been found that certain dipeptide compounds possess an intense sweetness. Examples of these compounds are set forth in U.S. Pat. Nos. 3,475,403 issued Oct. 28, 1969, 3,492,131 issued Jan. 27, 1970, and in the following foreign patents; Republic of South Africa Pat. Nos. 695,083 published July 12, 1969, 695,910 published Aug. 14, 1969 and German Pat. No. 2,054,545 published May 19, 1971. Generically, these compounds are represented by the formula: ##STR1## wherein R represents the lower alkyls, lower alkyaryls and cycloalkyls; n stands for integers 0-5; R.sub.1 represents a) phenyl group, b) lower alkyls, c) cycloalkyls, d) R.sub.2 ##STR2## where R.sub.2 is hydroxy, lower alkoxy, lower alkyl, halogen, e) S(O).sub.m (lower alkyl) WHERE M IS 0, 1 OR 2 AND PROVIDED N IS 1 OR 2, F) R.sub.3 ##STR3## where R.sub.3 represents an hydroxy or alkoxy and g) ##STR4## SINGLE OR DOUBLE UNSATURATED CYCLOALKYLS WITH UP TO EIGHT CARBONS. Most suitable among these compounds are the lower alkyl esters of aspartyl phenylalanine (U.S. Pat. No. 3,492,131) wherein the stereochemical configuration is DL-L, L-L, DL-DL, or L-DL. Illustrative of the lower alkyl esters are methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl and the branched chain groups isomeric therewith, with the methyl ester being the most preferred embodiment.
These dipeptides of Formula I have significant sweetening properties. Problems have arisen however, with the use of these compounds in dry systems in that their rate of solution into aqueous medium is markedly slower than sucrose, as exemplified by the methyl ester of L-aspartyl-L-phenylalanine.